Vibrator damping of vehicle path

ABSTRACT

Track supporting apparatus for vehicles to dampen vibrations arising as a result of vehicle movement on the track. The apparatus comprises a bottom plate which extends in the longitudinal direction of the track and which is supported by an elastic support means. At least one upper plate is disposed on the bottom plate, with a damping layer interposed between the bottom plate and the upper plate. A further means is provided for inhibiting relative lateral movement between the bottom plate and the upper plate. The damping layer may comprise a layer of viscoelastic material which is very thin relative to the thickness of the plates.

United States Patent [191 Egerbork et a1. 7

- [451 Feb. 5, 1974 4] VIBRATOR DAMPING OF VEHICLE PATH [73] Assignee: Akustikbyran Ab, Stockholm,

Sweden 22 Filed: May 25, 1971 21 Appl.No.: 146,777

[30] Foreign Application Priority Data May 28, 1970 Sweden 7356/70 [52] US. Cl. 238/2, 238/283 [51] Int. Cl.....; E0lb 1/00 I [58] Field of Search... 238/1, 2, 3, 283, 5, 382, 264

[56] References Cited UNITED STATES PATENTS 3,289,941 12/1966 Sonnevillem 238/116 3,576,293 4/1971 Landis et al. 238/283 3,550,850 12/1970 Sonneville 238/283 1,766,367 6/1930 Weller 238/5 2,719,676 10/1955 Prater 238/283 3,587,964 6/1971 Cork 238/2 2,420,833 5/1947 Monroe 238/2 Primary Examiner-Gerald- M. F orlenza Assistant Examiner-Richard A. Bertsch Attorney, Agent, or Firm-Sommers and Young [5 7] ABSTRACT Track supporting apparatus for vehicles to dampen vibrations arising as a'result of vehicle movement on the track. The apparatus comprises a bottom plate which extends in the longitudinal direction of the track and which is supported by an elastic support means. At least one upper plate is disposed on the bottom plate, with a damping layer interposed between the bottom plate and the upper plate. A further means is provided for inhibiting relative lateral movement between the bottom plate and the upper plate. The damping layer may comprise a layer of viscoelastic material which is very thin relative to the thickness of the plates.

5 Claims, 2 Drawing Figures The present invention relates to a device in path for motor vehicles for damping of vibrations arising from traffic and for preventing the transmission of these vibrations to the ground and environment of the path. A problem that is noticed more and more in the society of today is the disturbing noise arising from traffic with various means of conveyance. This applies particularly to rail vehicles and above all to subway trains which, as a rule, are driven in tunnels below the ground on which the dwelling-houses rest and through which vibrations from the traffic are transmitted to the buildings to cause inconvenience there in the form of noise. Such inconvenience is frequently caused, also by vehicles being driven on strongly vibrating concrete constructions, bridges etc., in direct connection with dwelling-houses.

It is the object of the invention to reduce the noise arising from vehicletraffic and to-limit the vibration transmission to the ground of the path as well as the sound radiation from the parts of the path set into vibration. This is achieved by the device of the invention, which embodies the characterizing features set forth in the following claims.

The invention will be described with reference to the drawing, in which FIG. 1 shows a section through a part of a path for rail vehicles and FIG. 2 shows a detail of the same.

In FIG. 1, the reference character designates the bedrock and 2 a concrete smoothing layer on which a preferablycontinuous bottom plate 3 of concrete extending in the longitudinal direction of the path is adapted. Between the plate 3 and the smoothing layer 2, isolator arrangements 4 of preferably viscoelastic material such as rubber are placed. On each side of the concrete plate 3 support constructions S'are mounted in the smoothing layer 2 at suitable distance in the longitudinal direction of the path, between which and the plate 3 elastic support means 6 are arranged intended for taking up lateral forces, above all in curves on the path.

As shown, the profile of the bottom plate 3 is substantially U-shaped with relatively short U-legs 7. Between these a central upper plate 8 of concrete is adapted, whose centre linesubstantially coincides with that of the plate 3, and on each side thereof with some interspace to the central plate 8 and the U-legs 7 there is a concrete body 9. The upper central plate 8 and the concrete bodies 9 have substantially the same extension in longitudinal direction as the bottom plate 3.

Between the bottom plate 3 and the upper plate 8 a thin layer of a so-called absorbate (a damping mass) 10 is adapted, i. e., a viscoelasticrnaterial, which for instance may be arranged as an aggregate of two plates and an intermediate layer of a viscoelastic material. In this layer, which is also called shearing layer, the great energy absorbing ability of the material, i.e., damping ability, is utilized, when it is exposed to shearing. In the space between the upper plate 8 and the bodies 9 absorbates 11 are adapted in a corresponding manner. In the interspace between the bodies 9 and the bottom plate 3 and its legs 7 an elastic material is inserted, for instance in the form of corrugated rubber sheet 12. The centre plate 8 as well as the concrete bodies 9 thus rest freely on the bottom plate 3 and between its legs 7 and are separated by said so-called absorbates 10, 11 and the rubber sheets 12 provided with ridges.

On the plate 8 rails 13 are adapted in a suitable manner, on which wheels 13 and a shaft 15 of a rail vehicle are shown. A current rail 16 with safety means 17 is also arranged in a suitable manner at one longitudinal side of the bottom plate.

In response to railway traffic on the rails 13 the resulting vibrations are transmitted to the upper plate 8 on which the rails rest. The rails can also be replaced with sliding paths, air cushion rails an d the like for other types of vehicles.

The device functions in such a way that the bending waves spreading from a vehicle in horizontal and vertical direction in the plate 8 are strongly damped by the presence of the shearing layers 10 and 11. The shearing layers will reach their full effect only by the presence of the supporting bottom plate 3 and of the unloaded passive bodies 9. The strong damping in the shearing layers cause the development of internal natural vibrations in the elastically arranged path 3, 8, 9 to be greatly reduced. This is a prerequisite in order that the vibration isolation by means of the isolators 4 should act effectively and that the direct air-sound radiation from the path should be kept at a low level.

The rubber layers 12 are provided to disconnect the bodies 9 from the motion of the bottom plate 3 and the upper plate 8.

For reasons of economy inmanufacturing, it can be advantageous that the plate 8 is longitudinally divided into smaller blocks, which then preferably are connected with suitable means preventing relative motion in the longitudinal direction of the path.

The device of the invention can of course be used for other parts of the path than tunnels. Thus, it is for instance very-advantageous at bridges, which, as is wellknown, heavily intensify traffic vibrations and radiate disturbing noise through the air. Atleast at shorter spans of bridges the bottom plate 3 can advantageously form the supporting element of the bridge.

What we claim is:

1. Track supporting apparatus for vehicles for damping vibrations arising as a result of vehicle movement on the track and for substantially preventing transmission of such vibrations to the ground and to the surroundings of the track comprising,

a bottom plate extending in the longitudinal direction of the track,

elastic support means for supporting said bottom plate without rigid contact with the ground,

at least one upper plate disposed on said bottom plate,

a damping layer interposed between said bottom plate and said upper plate,

and means for inhibiting relative lateral movement between said bottom plate and said upper plate,

said damping layer including a layer of viscoelasticv material which layer is very thin relative to the thickness of the plates, whereby shear stresses are developed in said visoelastic material when relative lateral movement takes place between the upper and bottom plates and when they oscillate in bending modes. I 2. The track supporting apparatus of claim 1, wherein a body for damping substantially horizontal vibrations is disposed on said bottom plate at each side 4. The track supporting apparatus of claim 1, wherein said elastic support means for said bottom plate comprises a plurality of rubber elements.

5. The track supporting apparatus of claim 1, wherein said damping layer comprises a viscoelastic material disposed between two metal plates.

V 3 3? UNITED STATES PATENT OFFICE -CERTIFICATE OF CORRECTION Patent No. '3, 796,078 Dated February ,5, 1974 v a Bo Mal te I staffan Egerborg, Goran Robert Gadefelt,

Inventofls) Gunnar Ingem'ar Hagbjer, and Kjell Knut Ingvar Spang It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

' The names of the first and fourth inventors are shown as "30' Malte S.. Egerbork" and 'tKj'ett Knut I. Spang" ,respe'cti ve ly; They should be I H lt 5 Eg bo gu v and 'Kj e ll Knut I. Spang";

Thet itle of the patent shouldbe changed from "Vibrator Damping of Vehicle Path" to "Vibration Damping oi Vehicle Path' Signed and sealed this 3rd day of December 1974.

(.SEAL) Attest I-icCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents 

1. Track supporting apparatus for vehicles for damping vibrations arising as a result of vehicle movement on the track and for substantially preventing transmission of such vibrations to the ground and to the surroundings of the track comprising, a bottom plate extending in the longitudinal direction of the track, elastic support means for supporting said bottom plate without rigid contact with the ground, at least one upper plate disposed on said bottom plate, a damping layer interposed between said bottom plate and said upper plate, and means for inhibiting relative lateral movement between said bottom plate and said upper plate, said damping layer including a layer of viscoelastic material which layer is very thin relative to the thickness of the plates, whereby shear stresses are developed in said visoelastic material when relative lateral movement takes place between the upper and bottom plates and when they oscillate in bending modes.
 2. The track supporting apparatus of claim 1, wherein a body for damping substantially horizontal vibrations is disposed on said bottom plate at each side of said upper plate, said body being supported by an elastic layer, and a damping layer disposed between said upper plate and each said body, said damping layers including a visoelastic material.
 3. The track supporting apparatus of claim 1 wherein said means for inhibiting lateral movement compriss shoulders directed upwardly from the bottom plate, the profile of said bottom plate being substantially U-shaped, said upper plate and said bodies being located between said shoulders.
 4. The track supporting apparatus of claim 1, wherein said elastic support means for said bottom plate comprises a plurality of rubber elements.
 5. The track supporting apparatus of claim 1, wherein said damping layer comprises a viscoelastic material disposed between two metal plates. 